thirdparty/scummvm
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RISCOS: Use dynamic areas for data and application space for plugins

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We only use application space in 26-bits (legacy) mode.
This commit is contained in:
Le Philousophe 2022-07-15 23:36:50 +02:00 • committed by Cameron Cawley
parent 35920b9e7e
commit 57fc1f91c8
2 changed files with 57 additions and 1 deletions
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52
backends/plugins/riscos/riscos-provider.cpp
View file

@ -32,6 +32,18 @@
#include <kernel.h>
#include <swis.h>
// By declaring this variable we force libunixlib to always use dynamic areas for data allocations
// This frees up space for plugins and allows to have plenty of space for data
const char *const __dynamic_da_name = "ScummVM Heap";
// HACK: These two function are part of private API in libunixlib
// They let allocate and free data in the application space where the stack is placed below 64MB
// When using malloc with big chunks we end up in memory mapped areas above 64MB
extern "C" {
extern void *__stackalloc (size_t __size);
extern void __stackfree (void *__ptr);
}
// HACK: This is needed so that standard library functions that are only
// used in plugins can be found in the main executable.
void pluginHack() {
@ -75,8 +87,48 @@ protected:
};
/**
* On 26-bit RISC OS, plugins need to be allocated in the first 64 MB
* of RAM so that it can be executed. This may not be the case when using
* the default allocators, which use dynamic areas for large allocations.
*/
class RiscOSDLObject_AS : public RiscOSDLObject {
protected:
void *allocateMemory(uint32 align, uint32 size) override {
// Allocate with worst case alignment in application space
void *p = __stackalloc(size + sizeof(uintptr) + align - 1);
void *np = (void *)(((uintptr)p + align - 1) & (-align));
*(uintptr *)((byte *)np + size) = (uintptr)p;
debug(8, "Allocated %p while alignment was %d: using %p", p, align, np);
return np;
}
void deallocateMemory(void *ptr, uint32 size) override {
void *p = (void *)*(uintptr *)((byte *)ptr + size);
debug(8, "Freeing %p which was allocated at %p", ptr, p);
__stackfree(p);
}
};
RiscOSPluginProvider::RiscOSPluginProvider() : _is32bit(false) {
__asm__ volatile (
"SUBS %[is32bit], r0, r0\n\t" /* Set at least one status flag and set is32bits to 0 */
"TEQ pc, pc\n\t" /* First operand never contains flags while second one contains them in 26-bits only */
"MOVEQ %[is32bit], #1\n\t" /* Set to 1 only if EQ flag is set */
: [is32bit] "=r" (_is32bit)
: /* no inputs */
: "cc");
}
Plugin *RiscOSPluginProvider::createPlugin(const Common::FSNode &node) const {
if (_is32bit) {
return new TemplatedELFPlugin<RiscOSDLObject>(node.getPath());
} else {
return new TemplatedELFPlugin<RiscOSDLObject_AS>(node.getPath());
}
}
#endif // defined(DYNAMIC_MODULES) && defined(RISCOS)

4
backends/plugins/riscos/riscos-provider.h
View file

@ -28,7 +28,11 @@
class RiscOSPluginProvider : public ELFPluginProvider {
public:
RiscOSPluginProvider();
Plugin *createPlugin(const Common::FSNode &node) const;
private:
bool _is32bit;
};
#endif // BACKENDS_PLUGINS_RISCOS_PROVIDER_H